In a Wideband Code Division Multiple Access (WCDMA) system, the transmit power required by an Enhanced Dedicated Channel Dedicated Physical Data Channel (E-DPDCH) can be obtained according to an E-DPDCH gain factor. The E-DPDCH gain factor may be calculated by an extrapolation formula using one reference E-DCH Transport Format Combination (E-TFC). The extrapolation formula is as follows:
                              β                      ed            ,            i            ,            harq                          =                              β                          ed              ,              ref                                ⁢                                                    L                                  e                  ,                  ref                                                            L                                  e                  ,                  i                                                              ⁢                                                                      K                                      e                    ,                    i                                                                    K                                      e                    ,                    ref                                                                        ·                          10                              (                                                      Δ                    ⁢                                                                                  ⁢                    harq                                    20                                )                                                                        (        1        )            
In the formula above, βed,ref denotes the E-DPDCH gain factor of the reference E-TFC; Le,ref denotes the number of E-DPDCH used for the reference E-TFC; Le,I denotes the number of E-DPDCH used for the i:th E-TFC (that is, the i:th E-TFC is corresponding to the E-DPDCH whose E-DPDCH gain factor is currently to be obtained); if a spreading factor of E-DPDCH is 2, Le,i and Le,ref denote the number of channels assuming a spreading factor of E-DPDCH is 4; Ke,ref denotes the transport block size of the reference E-TFC; Ke,i denotes the transport block size of the i:th E-TFC; and Δharq denotes an offset of a Hybrid Automatic Repeat Request (HARQ), and is specified by the upper layer. Table 1 lists the values of Δharq.
TABLE 1Δharq Signal ValueΔharq Power Offset (dB)66554433221100
After the uplink 16 Quadrature Amplitude Modulation (16QAM) mode is introduced into the WCDMA system, the uplink service rate increases to 11.52 Mbps. With the increase of the service rate, a formula is put forward for calculating the E-DPDCH gain factor under high rate services. This formula uses two reference E-TFCs, and is called an interpolation formula. The interpolation formula is as follows:
      β          ed      ,      i      ,      harq        =                              L                      e            ,            ref            ,            1                                    L                      e            ,            i                                ·                  (                                            (                                                                                                                  L                                                  e                          ,                          ref                          ,                          2                                                                                            L                                                  e                          ,                          ref                          ,                          1                                                                                      ⁢                                          β                                              ed                        ,                        ref                        ,                        2                                            2                                                        -                                      β                                          ed                      ,                      ref                      ,                      1                                        2                                                                                        K                                          e                      ,                      ref                      ,                      2                                                        -                                      K                                          e                      ,                      ref                      ,                      1                                                                                  )                        ⁢                          (                                                K                                      e                    ,                    i                                                  -                                  K                                      e                    ,                    ref                    ,                    1                                                              )                                +                      β                          ed              ,              ref              ,              1                        2                          )              ·          10              (                              Δ            ⁢                                                  ⁢            harq                    20                )            
In the formula above, βed,i,harq denotes the E-DPDCH gain factor; Le,i denotes the number of E-DPDCH in non-compressed mode; βed,ref,1 and βed,ref,2 denote the E-DPDCH gain factors of the first and second reference E-TFCs respectively; Le,ref,1 and Le,ref,2 denote the number of E-DPDCHs used for the first and second reference E-TFCs; if the spreading factor of E-DPDCH is 2, Le,ref,1 and Le,ref,2 denote the number of channels assuming the spreading factor of E-DPDCH is 4; Ke,ref,1 and Ke,ref,2 denote the transport block sizes of the first and second reference E-TFCs; Ke,i denotes the transport block size of the i:th E-TFC; and Δharq denotes the offset of the HARQ, and is specified by the upper layer.
In the prior art, if the Transmission Time Interval (TTI) is 10 ms in the compressed mode, the calculation of the E-DPDCH gain factor comes in two scenarios: the current frame is a compressed frame, and the current frame is a normal frame.
At least the following problems are found in the prior art:                in the prior art The E-DPDCH gain factor calculated out in compressed mode does not reflect the transmit power required by the E-DPDCH accurately, and the transmit power required by the E-DPDCH which is determined according to the E-DPDCH gain factor is not accurate either. Consequently, part of the transmit power of E-DPDCH is wasted and therefore the system capacity is reduced.        